Add CLI interface

README.md

@@ -11,9 +11,15 @@ vulkan-zig attempts to provide a better experience to programming Vulkan applica
 vulkan-zig is automatically tested against the latest vk.xml and zig, and supports vk.xml from version 1.x.141.
 
 ## Features
+### CLI-interface
+A CLI-interface is provided to generate vk.zig from the [Vulkan XML registry](https://github.com/KhronosGroup/Vulkan-Docs/blob/master/xml), which is built by default when invoking `zig build` in the project root. To generate vk.zig, simply invoke the program as follows:
+```
+$ zig-cache/bin/vulkan-zig-generator path/to/vk.xml output/path/to/vk.zig
+```
+This reads the xml file, parses its contents, renders the Vulkan bindings, and formats file, before writing the result to the output path. While the intended usage of vulkan-zig is through direct generation from build.zig (see below), the CLI-interface can be used for one-off generation and vendoring the result.
+
 ### Generation from build.zig
-Vulkan bindings can be generated directly from the [Vulkan XML registry](https://github.com/KhronosGroup/Vulkan-Docs/blob/master/xml) build.zig at compiletime, by using the provided
-vulkan generation step:
+Vulkan bindings can be generated from the Vulkan XML registry at compile time with build.zig, by using the provided Vulkan generation step:
 ```zig
 const vkgen = @import("vulkan-zig/generator/index.zig");
 
@@ -236,5 +242,5 @@ Upon compilation, glslc is then invoked to compile each shader, and the result i
 A partial implementation of https://vulkan-tutorial.org is implemented in [examples/triangle.zig](examples/triangle.zig). This example can be ran by executing `zig build run-triangle` in vulkan-zig's root.
 
 ## See also
-* (Outdated) implementation of https://vulkan-tutorial.org using translate-c: https://github.com/andrewrk/zig-vulkan-triangle.
+* Implementation of https://vulkan-tutorial.org: https://github.com/andrewrk/zig-vulkan-triangle.
 * Alternative binding generator: https://github.com/SpexGuy/Zig-Vulkan-Headers

build.zig

@@ -75,6 +75,12 @@ pub fn build(b: *Builder) void {
 
     const target = b.standardTargetOptions(.{});
     const mode = b.standardReleaseOptions();
+
+    const generator_exe = b.addExecutable("vulkan-zig-generator", "generator/main.zig");
+    generator_exe.setTarget(target);
+    generator_exe.setBuildMode(mode);
+    generator_exe.install();
+
     const triangle_exe = b.addExecutable("triangle", "examples/triangle.zig");
     triangle_exe.setTarget(target);
     triangle_exe.setBuildMode(mode);

generator/main.zig

@@ -0,0 +1,74 @@
+const std = @import("std");
+const generate = @import("vulkan/generator.zig").generate;
+
+const usage = "Usage: {} [-h|--help] <spec xml path> <output zig source>\n";
+
+pub fn main() !void {
+    const stderr = std.io.getStdErr();
+    const stdout = std.io.getStdOut();
+
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const allocator = &arena.allocator;
+
+    var args = std.process.args();
+    const prog_name = try args.next(allocator) orelse return error.ExecutableNameMissing;
+
+    var maybe_xml_path: ?[]const u8 = null;
+    var maybe_out_path: ?[]const u8 = null;
+
+    while (args.next(allocator)) |err_or_arg| {
+        const arg = try err_or_arg;
+
+        if (std.mem.eql(u8, arg, "--help") or std.mem.eql(u8, arg, "-h")) {
+            @setEvalBranchQuota(2000);
+            try stderr.writer().print(
+                \\Utility to generate a Zig binding from the Vulkan XML API registry.
+                \\
+                \\The most recent Vulkan XML API registry can be obtained from
+                \\https://github.com/KhronosGroup/Vulkan-Docs/blob/master/xml/vk.xml,
+                \\and the most recent LunarG Vulkan SDK version can be found at
+                \\$VULKAN_SDK/x86_64/share/vulkan/registry/vk.xml.
+                \\
+                \\
+                ++ usage,
+                .{ prog_name },
+            );
+            return;
+        } else if (maybe_xml_path == null) {
+            maybe_xml_path = arg;
+        } else if (maybe_out_path == null) {
+            maybe_out_path = arg;
+        } else {
+            try stderr.writer().print("Error: Superficial argument '{}'\n", .{ arg });
+        }
+    }
+
+    const xml_path = maybe_xml_path orelse {
+        try stderr.writer().print("Error: Missing required argument <spec xml path>\n" ++ usage, .{ prog_name });
+        return;
+    };
+
+    const out_path = maybe_out_path orelse {
+        try stderr.writer().print("Error: Missing required argument <output zig source>\n" ++ usage, .{ prog_name });
+        return;
+    };
+
+    const cwd = std.fs.cwd();
+    const xml_src = cwd.readFileAlloc(allocator, xml_path, std.math.maxInt(usize)) catch |err| {
+        try stderr.writer().print("Error: Failed to open input file '{}' ({})\n", .{ xml_path, @errorName(err) });
+        return;
+    };
+
+    const out_file = cwd.createFile(out_path, .{}) catch |err| {
+        try stderr.writer().print("Error: Failed to create output file '{}' ({})\n", .{ out_path, @errorName(err) });
+        return;
+    };
+    defer out_file.close();
+
+    var out_buffer = std.ArrayList(u8).init(allocator);
+    try generate(allocator, xml_src, out_buffer.writer());
+    const tree = try std.zig.parse(allocator, out_buffer.items);
+
+    _ = try std.zig.render(allocator, out_file.writer(), tree);
+}

generator/vulkan/build_integration.zig

@@ -75,6 +75,6 @@ pub const GenerateStep = struct {
         try cwd.makePath(dir);
         const output_file = cwd.createFile(self.package.path, .{}) catch unreachable;
         defer output_file.close();
-        _ = try std.zig.render(self.builder.allocator, output_file.outStream(), tree);
+        _ = try std.zig.render(self.builder.allocator, output_file.writer(), tree);
     }
 };